Consolidated Statements Of Cash Flows (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2014		Dec. 31, 2013		Dec. 31, 2012
Cash Flows from Operating Activities:
Net income	$ 181,951		$ 187,794		$ 178,287
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	58,888		54,596		52,408
Gain on disposition of pharmaceutical product lines					(3,500)
Provision for uncollectible accounts	2,035		1,601		1,108
Provision for (benefit of) deferred income taxes	830		2,073		(1,970)
Share-based compensation expense	18,099		16,539		15,952
Other	(160)		614		410
Tax benefit from share-based compensation arrangements	(16,078)		(14,158)		(14,676)
Changes in assets and liabilities:
Accounts receivable	(3,626)		(15,946)		3,487
Inventories	(38,310)		(1,347)		(17,208)
Other assets	(25,073)		(4,325)		3,933
Accounts payable	6,703		(4,399)		(2,898)
Accrued liabilities	36,392		16,512		187
Deferred revenue	14,195		6,442		6,888
Net cash provided by operating activities	235,846		245,996		222,408
Cash Flows from Investing Activities:
Purchases of property and equipment	(60,523)	[1]	(77,612)	[1]	(57,618)
Proceeds from disposition of pharmaceutical product lines			3,500		3,000
Proceeds from sale of equity investment	5,400
Proceeds from sale of property and equipment					45
Acquisitions of intangible assets	(175)		(1,024)		(900)
Acquisitions of a business, net of cash acquired	(25,115)		(10,923)		(2,658)
Net cash used by investing activities	(80,413)		(86,059)		(58,131)
Cash Flows from Financing Activities:
Borrowings (payments) on revolving credit facilities, net	272,000		65,000		(31,000)
Issuance of senior notes	200,000		150,000
Debt issue costs	(1,406)		(976)
Payment of notes payable	(1,394)		(1,107)		(917)
Repurchases of common stock	(618,158)		(367,761)		(132,268)
Proceeds from exercises of stock options and employee stock purchase plans	29,442		38,235		24,166
Tax benefit from share-based compensation arrangements	16,078		14,158		14,676
Net cash used by financing activities	(103,438)		(102,451)		(125,343)
Net effect of changes in exchange rates on cash	(8,517)		(2,414)		1,157
Net increase in cash and cash equivalents	43,478		55,072		40,091
Cash and cash equivalents at beginning of period	279,058		223,986		183,895
Cash and cash equivalents at end of period	322,536		279,058		223,986
Supplemental Disclosures of Cash Flow Information
Interest paid	12,284		5,024		3,944
Income taxes paid	60,239		67,721		68,921
Supplemental Disclosure of Non-Cash Information:
Market value of common shares received from employees in connection with share-based compensation - see Note 17	5,809		4,548		4,662
Receivable on disposition of pharmaceutical product lines					$ 3,500

[1] Expenditures for long-lived assets exclude expenditures for intangible assets. See Note 3 for information regarding acquisitions of intangible assets during the years ended December 31, 2014, 2013 and 2012.